In contribution to advancements in integrated circuits and system-on-package (SOP) techniques, the required area of a system ground plane of an internal communication circuit module in a cell phone is remarkably reduced. Thus, communication modules for different system band operation could be integrated into one single mobile communication device. However, other issues such as limited antenna space within a cell phone and electromagnetic compatibility problems between antenna elements or system modules of different applications may arise. System ground planes of different mobile communication devices usually come in shapes with different defects, which are disadvantages for exciting lower band resonant modes of WWAN (Wireless Wide Area Network) antennas in the mobile communication devices. This is because a complete ground plane could effectively decrease overall quality factors of antennas and make the antennas to generate wider operating bandwidths at lower frequency bands. As a result, there is a challenge for the design of multi-band WWAN antennas due to the effect that an incomplete ground plane imposes on the excitation of resonant modes at lower frequency bands. Further, since impedance bandwidths of resonant modes of an antenna would be easily affected by size variations of the ground plane connected, a time-consuming process for adjusting dimensions of the antenna is frequently needed for adapting to different sizes of ground planes of mobile communication devices.